Electron tube



March 28, 1939.

ELECTRON TUBE Filed Aug. 8, 1932 INVENTOR FRITZ MICHELSSEN ATTORNEYFiMICl- IELSSEN 2,151,789

Patented Mar. 28, 1939 UNITED STATES PATENT OFFICE ELECTRON TUBE FritzMiohelssen,

Berlin, Germany, assignor to Telefunken Gesellschaft fiir DrahtloseTelegraphie m. b. H., Berlin, Germany, a corporation of GermanyApplication August 8, 1932, Serial No. 627,928 In Germany August 25,1931 1 Claims. (01. 250-141 impinge upon the center of the fluorescentscreen surface which it is to strike, as long as no deflective forcesare brought to act upon the electron pencil.

An arrangement of this sort is well known in the prior art and usuallyconsists of a tube wherein the axis of the electrode system generatingand deflecting the cathode-ray pencil coincides with the central axis ofthe vessel so that the projection of the system of deflector plates uponthe fluorescent screen comes to lie in the center thereof. For a greatmany purposes this arrangement is of advantage, for instance, where therecording of alternating current curves, recording of hysteretic loopsor the like, is concerned.

According to the present invention, however,

I this type of revolution-symmetric construction usually employed in theprior art is abandoned. Such a scheme is of great advantage for a numberof other practical applications of a Braun or cathode ray tube. Ininstances, whenever the point is (as, e. g., in television work) to scanthe screen, starting from the origin of a coordinate system, in twodirections at right angles to each other by means of a cathode raypencil or spot, it is of greater advantage to remove the starting spotof the cathode ray pencil from the center of the screen towards the edgeor margin or into a corner of the scanning surface. In the case of astructure, that is, the form of construction, presenting rotationalsymmetry, scanning from a point as stated can be accomplished only byfirst bringing the pencil to a point close to the edge of the screen bythe action of electric or magnetic deflection. If, in order to avoid theirregular or non-uniform luminous excitation of the screen caused bysinuous alternating current potentials recourse is had to what is knownas Kipp oscillations whose potentials cause the spot to scan the surfacein two directions, starting from a coordinate origin, then specialcircuit means must be provided whereby the origin of the coordinatesystem, that is, the stationary spot of the pencil in the absence ofdeflecting Kipp oscillations, is shifted towards the edge of theluminescent screen. The provision of such means is obviated according tothe present invention.

According to this invention the construction of the tube is made so thatthe electrode system, cross-sectionally speaking, does not appear to beprojected upon the center of the screen, but at a point close to theborder thereof. In other words,.the trace or contour of the cathode raypencil is not situated in the center of the screen surface but rathermarginally on the part of the impinging surface to be scanned thereby,in the absence of deflective fields. This is accom plishable by asuitable arrangement of the electrode system inside the tube or bychoosing convenient forms for the tube or vessel. The most preferableplan in this connection is to proceed in such a way that the axis of theelectrode system falls outside the median axis of the vessel.

The basic idea of the inventionis illustrated by way of example by theaccompanying drawing, wherein:

Fig. 1 represents a longitudinal section through the tube; Fig. 2represents a cross-section of one end of the tube; and Fig. 3 representsa modifled form of the tube shown by Fig. 1.

The glass support (not shown) carrying the tube cathode and anodeelectrodes l and 3 may be welded fast in the glass bulb 4 eccentricallyrather than concentrically or symmetrically. The electric or magneticdeflector systems 5 and 1 disposed either inside or outside the vessel,according to the present disclosure, should then be so arranged that theelectron pencil 9, in the directions at right angles to each other, isable to scan the same distance as far as the next edge of the screen II.

In such an eccentric form of tube there arises this drawback that whenscanning the entire picture surface, thepunctiform pencil 9 does notexhibit throughout the same sharpness owing to the fact that thedistances or the paths passed by the pencil are of dissimilar lengths.Furthermore, owing to the steadily changing angle of the pencil relativeto the picture surface there might easily occur a distortion or anunequally intense excitation of the picture where large areas areconcerned.

This dimculty as outlined in Fig. 3 is obviated by arranging theeccentric construction of the electrode system relative to the picturesurface and also the impinging surface at such an angle of inclinationrelative to the nondeflected pencil that like length of rays is insuredfor all directions when the pencil is deflected.

Having now described my invention, what I claim and desire to secure byLetters Patent is the following:

1. A cathode ray tube comprising an electrode system including anelectron source and a cooperatively arranged anode through which thedeveloped electrons are projected as an electron beam, screen structurepositioned within the tube eccentrically with respect to the axis of theelectrode system, said screen structure being adapted to becomefluorescent under the influence of the electron beam, and deflectingmeans axially aligned with the beam developing electrode system andpositioned eccentrically with respect to the screen to cause whenelectrical energy is supplied thereto the generated electron beam totraverse the screen structure.

2. A cathode ray tube comprising an electrode system including anelectron source and a cooperatively arranged anode through which thegenerated electrons are projected as an electron beam, an electronresponsive screen structure located within the tube and positionedeccentrically and angularly tilted with respect to the electrode system,and deflecting means axially aligned with respect to the electrodesystem to cause when electrical energy is applied thereto the generatedelectron beam to traverse the screen structure.

3. A cathode ray device comprising an envelope including an electrodesystem comprising a cathode and an anode for generating an electron beamadapted to be projected axially therethrough, screen structure providedat the opposite end of the envelope opposite the source of the electronbeam and positioned eccentrically with respect to the axis along whichthe generated electron beam is projected so that the electron beam inits normal uncontrolled path impinges only upon an edge portion of thescreen, and deflecting means axially aligned with respect to theelectrode system for causing the electron beam generated to traverse thescreen under the application of suitable deflecting voltages upon thedeflecting means.

4. An electron tube comprising a fluorescent screen positioned at oneend of the tube substantially normal to the longitudinal axis of thetube, gun structure for developing a beam of electrons mounted at theopposite end of the tube in an angular position relative to thelongitudinal tube axis for directing the normal, undeflected beam uponthe edge portion of the screen, only, and an electron beam deflectingsystem supported in axial alignment with the gun structure and alsopositioned at an angle with respect to the longitudinal tube axis.

5. In an electron tube, a fluorescent screen positioned at one end ofthe tube in a position substantially normal to the longitudinal axis ofthe tube, an electron gun structure positioned at the opposite end ofthe tube and arranged in an angular position relative to the tube axisso that the electron beam passing beyond the gun structure in thedirection of the screen is normally incident upon the edge portion ofthe screen and an electron beam deflecting system supported in axialalignment with the gun structure and also positioned at an angle withrespect to the tube axis.

6. In an electron tube, screen structure adapted to emit light upon thesubjection thereof to an electron beam, an electron source, an anodearranged in co-operative relationship with said electron source so as toproject a beam of electrons along a predetermined path correspondingsubstantially to'the line drawn through the center of the source and theanode, said path being angularly displaced with respect to thelongitudinal axis of the tube, and an electron beam deflecting systemsupported within the tube in equalized relationship with respect to theelectron beam path so that the electron beam normally impinges upon theedge portion of the screen structure.

'7. In electron tubes, a viewing screen, means for producing an electronbeam and directing the developed electron beam toward the tube viewingscreen along a path angularly disposed relative to the longitudinal axisof the tube so that the beam in normal position impinges upon one edgeportion only of the screen, and a beam deflecting system in alignmentwith the normal path of the projected electron beam for causing thedeveloped beam upon the application of suitable electrical energy to thedeflecting system to sweep the entire screen structure.

FRITZ MICHZELSSEN.

